For many years, there has been a need to develop lighter and stronger materials to improve quality, safety, and efficiency in a vast array of industries, including but not limited to aerospace, automotive, marine, apparel, sporting goods, fiber optics, industrial safety, military and law enforcement, and electronics.
Since the 1950's, there have been numerous breakthroughs in the development of high performance fibers having many times the strength of steel at a fraction of the weight. Examples of such high performance fibers include but are not limited to polyester fibers (such as the products sold under the trade name Dacron®), nylon fibers, aramid fibers (such as the products sold under the trade names Kevlar®, Techora®, and Twaron®), carbon fibers, ultra high molecular weight polyethylene (“UHMWPE”) (such as products sold under the trade names Ceran®, Dyneema®, and Spectra®), liquid crystal polymers (“LCP”) (such as products sold under the trade name Vectran®) and (poly (p-phenylene-2,6-benzobisoxazole)) (“PBO”) (such as products sold under the trade name Zylon®), and polyethylene naphthalate PEN fibers (such as products sold under the trade name Pentex®). For many years, these high performance fibers have been used in woven and non-woven arrangements to form multilayered composites and laminated structures.
For example, WO 2012/018959 describes the problems with using the high performance fibers in a woven configuration. Specifically, the weaving processes induce crimp in the fibers, which cause stress concentrations and wear points that significantly reduce the strength and long term performance of the fabric.
U.S. Pat. No. 5,333,568 also describes the crimping problem with woven configurations, while describing a reinforced nonwoven laminate that utilizes a reinforcing sheet of unidirectional extruded fibers in which the reinforcing sheet or sheets form one or more uni-tapes laminated to outer layers of polyester film. The fibers are uniformly embedded in the uni-tape via an elastomeric polymer matrix. The low elasticity of the high performance fibers ensures that the laminate does not stretch under a load applied in the direction of the fiber orientation. While stretch resistance is a key parameter for applications such as sails, where the laminate must be flexible without deforming under a load, such stretch resistance is problematic when the laminate is used in a process that requires some material deformation to form three dimensional objects.
In many cases, the materials described in U.S. Pat. No. 5,333,568 are manufactured with two or four layers of UHMWPE fibers sandwiched between two outer layers of polyester, wherein the fibers are superimposed in non-bias (0°/90°) and bias (0°/90°/+45°/−45°) configurations in a variety of weights. Other outer layer materials that have been used with the UHMWPE fiber layers include elastomeric thermoset polymers (such as urethanes and silicones), thermoplastics (such as nylon), low density polyethylene, polypropylene, thermoplastic polyurethanes, and hot melt adhesives (such as polyolefins and polyamides).
While having a very low weight and high tensile strength, these materials have issues with crinkling, noise, unpleasant textures, and a lack of elasticity and softness. In short, the material has the look and feel of a crinkly plastic bag. Furthermore, in use, the materials often lack seam strength, stitch sheer strength, thread strength, UV resistance, and stretchability. For example, FIGS. 1 and 2 illustrate a shoe 28 formed with the material described in U.S. Pat. No. 5,333,568. As illustrated in these images, when the material described in U.S. Pat. No. 5,333,568 is placed over a shoe last to form a three dimensional shoe upper 26, the material was incapable of being stretched over the shoe last to create the three dimensional shoe upper shape. Rather, the material had to be cut and sewn in multiple places to form the rounded shape needed for the shoe upper 26.
U.S. Pat. No. 5,935,678 describes a laminate structure in sheet form with first and second arrays of high performance, unidirectionally-oriented fiber bundles. The second array of fiber bundles is cross-plied at an angle to the first array of fiber bundles. A polymeric film resides between the first and second cross-plied arrays of fiber bundles to adhere the first and second arrays of fiber bundles together. This design provides a rigid structure for use as a ballistic laminate structure, but is problematic when the laminate is used in a process that requires some material deformation to form three dimensional objects.
US 2013/0219600 describes a multilayer non-woven fabric material composed of two or four non-woven fiber sheets of aramide/polyethylene fibers, impregnated with resin and/or a filler material, and oriented at various angles, which is used for manufacturing protection garments. The superimposed non-woven fabric layers are not bonded or glued together as a way to provide a flexible material for use in protective garments. While this design provides the necessary flexibility for use in garments, the design is similar to the flexible design taught in U.S. Pat. No. 5,333,568, and therefore also does not provide the necessary elasticity when the laminate is used in a process that requires some material deformation to form three dimensional objects. Furthermore, because the fabric layers are not bonded or glued together, the material has minimal, if any, delamination strength.
Thus, it is desirable to provide a nonwoven multilayered composite and/or laminated structure, wherein each layer comprises unidirectional high performance fibers, which provides a very low weight material with high tensile strength and some elasticity so that the structure may be used in a process that requires some material deformation to form three dimensional objects. It is also desirable to incorporate such a multilayered material into shoes, and particularly into shoe uppers, in strategic locations to take advantage of the high strength and low weight of such a material.